This invention relates to a floatation apparatus and method, more particularly to a cyclonic-static micro-bubble floatation apparatus and method in which the separation of fine materials is improved.
Conventional floatation columns operate based on the theory so called as "air bubble mineralization by reverse collision", which provide the floatation columns an effective separation method with high separating selectivity. Because of lacking a mechanism of improving the separation and increasing the recovery, the columns generally need increased separating zones, i.e., the highness of the columns is increased, in order to enhance the recovery. Therefore, conventional floatation columns usually have a highness of as long as 8-10 m or more and the separation efficiency and recovery capacity are low frequently.
Recently, the techniques used in the floatation column, especially the techniques for micro-bubble generation, have been greatly developed, and the quality of the bubbles generated in the columns can basically meet the requirement of the floatation column separation, and provide good conditions for the column's stable performance. Therefore, the low separation efficiency and recovery capacity presently emerge as the most noticeable problems of the conventional floatation columns, and perhaps directly limit their further development and wider application.
As above mentioned, the low separation efficiency and recovery capacity of the conventional floatation columns is due to lack of a mechanism of separation and recovery improvement. The following three new types of floatation columns with a reformed structure have been developed for enhancement of air bubble mineralization, and their separation efficiencies and recovery capacities have been improved to a certain extent but not sufficient.
For instance, in Eur. Pat. Appl. EP. 146,235 (C1.B03D1/14), Jun. 23, 1985 "Apparatus and method for removing foam and entrained particles from pulp in a floatation cell", a floatation column with a shorter shell body is disclosed, in which bubble mineralization in intense turbulent conditions within pipes is applied and the floatation efficiency is higher, but separation is not complete and the tailings contains a lot of the floatable minerals due to the insufficient mineralization time and lack of a multi-circulation processing for separation in the apparatus.
For instance, in U.S. Pat. No. 4,529,834, a packing floatation column is disclosed, in which the separation efficiency increases due to the packing media, but the column is readily plugged and clogged and then its production capacity decreases. In this kind of the floatation column, coarse particles are usually difficult to be recovered and often lost in the tailings.
For instance, in Microcell Column, a part of processed pulp is introduced from the floatation column as operating medium of the bubble generator, forming a pulp circulation. However, the circulating pulp and the tailings removed have not been further separated within the column, and the pulp passed the bubble generator has not been further processed by a pipe floatation to improve the separation efficiency.
The mechanical floatation machines have usually been designed based on application of the mechanism of improving separation. For example, at the bottom regions of the floatation machines around their mechanical agitator (including the regions under the agitator blade and around it), a high pulp turbulence conditions are formed, resulting in intense collision between mineral particles and air bubbles, and a high-degree mineralization of the bubbles from different directions is achieved. And there is a pulp circulation around the agitator within machines, increasing chances of the collision and mineralization. Although the mechanical agitation and pulp turbulence increases the mineralization efficiency and recovery capacity of the machines, they also deteriorate the conditions for separation of mineralized bubbles at the same time, resulting in serious mechanical entrainment of non-target minerals in the concentrate product.
For instance, in "Floatation Apparatus for Achieving Floatation in a Centrifugal Field, Miller, Jan D. Eur. Patent Appl. EP47, 135 (C1.BO3D/14), a cyclonic separator is used in the separation processing of fine materials, but this apparatus do not comprise any column separation apparatus. Although the separation speed in the apparatus has been increased, its separation selectivity becomes worse and the outstanding advantage of floatation columns disappears.
All above literature does not mention explicitly or implicitly the combination of the column separator and the cyclonic separator, the combination of the cyclonic separation and the pipe floatation, as well as the combination of the column separator, the cyclonic separator and the pipe floatation applied in mineral processing.